The following description relates to a method of measuring damping of a work piece, and in particular, a method of measuring damping using a high speed camera or cameras.
Damping generally relates to the ability of a part to absorb energy when excited. Damping may be measured using a factor called a Q factor. A damping measurement may be used to assess vehicle brake noise propensity and provide a useful comparison to determine work piece vibration by capturing the ability of the work piece to absorb unwanted vibration energy. Damping measurements may be referred to using different terminology including, for example, damping factor, damping ratio, quality factor (“Q factor”), loss factor, tan delta, and/or specific damping capacity.
Current methods of damping measurement may involve exciting a part using an excitation device. An excitation device may include, for example, an impulse hammer or a shaker. Damping may be measured after the excitation device, such as the impulse hammer, strikes the work piece or part. A time and/or frequency response is then recorded using a sensor, such as an accelerometer and/or microphone. This data is processed to obtain a Q factor, which may also be referred to as a damping number. Since the damping number (Q factor) is dependent on the location on the work piece where the impulse hammer strikes, location of measurement on a brake rotor, and the frequency of vibration, it takes multiple measurements at different areas on the work piece to arrive at an optimum location to extract the numbers used to determine the Q factor. This type of iterative process of measuring may take an unsuitable period of time to complete. For example, the iterative process may take three or four minutes. In a production or lab environment, the delay due to measuring time may cause other delays. In order to reduce the measurement time, measurements may be made at multiple locations simultaneously. However, this requires a large number of sensors to be placed at or near the rotor. This increases the number of measurement channels needed.
Accordingly, it is desirable to measure damping during a reduced time period while using a limited number of sensors.